Hydraulic lathe center



July 2, 194-6. AR-r0 2,402,979

- HYDRAULIC LATHE CENTER I Filed Dec. 28, 1943 2 Sheets-Shae? 1 QQ. Z. UTHLQ [Bag To Inventor July 2, 1946. B r0 2,402,979 HYDRAULIC LATHE CENTER Filed Dec. 28, 1943 -2 Sheets-Sheet 2 1 WWW l rrs Luther A. Barto, Allentown, Pa. Application December 28, 1943, Serial No. 515,964

4 Claims. i

This invention relates to new and useful improvements in lathe centers, the principal object being to provide a hydraulic control of the pressure created by the heat expansion on the tail stock center of work or job to be turned or machined on small or large ngine lathes.

Another important object of the invention is to provide a hydraulic lathe center which is portable and can be easily applied to conventional lathes and which includes means for indicating and controlling work pressures at all times.

Another important object of the invention is to obviate the necessity of changing centers because of burning out and scoring of the same and correspondingly to preclude the necessity of changing such centers due to the overheating or scoring of the bearings carrying the same.

Other objects and advantages of the invention will become apparent to the reader of the following description.

in the drawings:

Figure 1 is a fragmentary side elevational view showing the improved center. v

Figure his a fragmentary longitudinal sectional view taken on the line 2-2 of Figure 1.

Figure 3 is a fragmentary top plan view of the structure shown in Figure l. v

Figure 4- s a cross section on the line 3- 3 of Figure 2.

Figure 5 is a fragmentary longitudinal sectional view through the adjustable valve.

Referring to the drawings wherein like numerals designate like parts, it can be seen that numeral 5 generally refers to the improved tailstock unit which consists of a case 5 from which a tapered shank l projects for disposition into the tailstock of the lathe which is generally referred to by numeral 8.

Numeral 9 denotes a tailstock center having a tip it and this center is disposed through a ball bearing assembly ll located within the outer end of the case '6, and a closure plate 112 secured in place by screws 93 abuts the outer portion of the bearing assembly H. The plate l2 contacts a lubricant seal it.

The center 9 has a circumferential rib or collar l 5 which abuts the inside of the bearing assembly I i, this as is clearly shown in Figure 2.

The inner end of the center 9 has a hollow piston structure It bearing against the same and urged to this position by a compression spring I I which is interposed between the inner end of the case 6 and a cup it which, in turn, bears against a leather cup 01' seal 19. Small opening 20 are provided in the piston to facilitate easy removal of the bearing cup. A plugged opening 2i is providcd in the case to allow clearance for slotting the keyway. Numeral 22 denotes a key for preventing rotation of the piston i6.

Inclined roller bearings 23 are provided in an assembly located within the piston and associated with the inner end of the. center 9 to take care of end thrust and also certain amount of radial pressure in addition'to that taken care of by the ball bearing assembly 8 l.

A grease fitting M is provided for the chber 25 and a bleeder valve 26 is provided for the chamber 2'71 at the opposite side of. the piston it. A small air vent 28 is provided for the chamber 25.

A tube 30 extends from a duct 35 communicating with the chamber 2? and this connects by a fitting 32 with a pressure gauge 33 and also by way of a fitting t iwith a valve35. From the valve 35 a pipe 36, extends to an adjustable valve 37 and this, in turn, is connected by way of a If-befitting 39 is connected to a hydraulic fluid reservoir ill and also by way of a, pipe 62 to a valve t3, the latteusbeing, in turn, connected by a pipe at to a fitting 415 between fitting 3t and a valve 446, the latter valve being connected by a ipe (it to a hand pump or the like iil. The hand pump it is in turn connected as at 59 to the fitting 39. The tank (it provides the requisite air-compression chamber therein for a purpose presently apparent.

The adjustable valve 3i consists of a case 5! having a header 52 in'which. is a valve seat 53 to which the pipe 36 extends. A tapered valve 5d operates against this seat and has a stem 55 projecting inwardly and around which is disposed a coiled spring 56. The spring 56 is interposed between the valve element 54! and a piston 51, the position of which can be adjusted by a feedable screw 58.

From the foregoing the operation of the device should now be readily understandable. A the work operated on by the lathe expands due to heat or the like, the center 9 i forced inwardly against the pressure of'the spring 6 7, and correspondingly the pressure of the fluid in the hydraulic system. Conversely, upon cooling of the work for any reason whatsoever, the spring I! will bias the lathe center 9 outwardly thereagainst to maintain a desired pressure on the work. This pressure may be regulated in accordance with the pressure indicated by gauge 35, fluid being fed from the fluid reservoir ll either through the pipe t2, the valve i3, and the pipe M to the pressure gauge 33 and the line 30 into the chamber 27, and controlled manually by means of the valve 43 in accordance with the pressure indicated on the gauge 33. Hy-

draulic pressure in the system may be relieved, as

required, by means of the valve 35, line 36, automatic valve 32, line 38, and fittings 39, 48, whereby the fluid may be returned to reservoir 4|, the pressure in the automatic valve 31 being governed by the position of the screw 58 as above described. I

Thus, it will be seen that automatic or manual constant pressure control against the center 9- may becontinuously maintained regardless of the expansion or contraction of the work due to heat.

'The gauge 33 indicates in pounds per square inch the hydraulical force or pressure developed in the tailstock. For example, if 800 pounds per square inch is needed for satisfactory operation of the unit and the work being turnedit may be controlled either by the automatic valv 32, or

the fluid reservoir in the manner previously described is insufficient to accomplish the same, the pump 48 may be manually actuated, the valves 43 and 35 being closed and the valve 46 open to accomplish this result by building up the fluid pressure to-such point that the piston, and correspondingly the associated lathe center 9 is returned to the desired position.

Thus, it will be seen that by means of the instant invention, pressure in the system forcing the lathe center 9 against the work may be maintained substantially'constant, regardless of the expansion or contraction of the work, occasioned by heat due to the speed of rotation of the work or the like. It will also be seen that there is herein provided an improved hydraulic lathe center accomplishing all the objects of this invention and others including many advantages of great practical utility and commercial importance.

While the foregoing specification sets forth the sion spring biasing said piston and said center outwardly .with respect to said cylinder, said means for supplying fluid under pressure including a conduit, a pressure recording gauge in said conduit, a plurality of conduits connecting said pressure gauge witha fluid pressure reservoir, and a manually operablevalve controlling admission of said fluid through one of said conduits.

2. In a center for lathes in combination, a hydraulic cylinder, means for supplying fluid under pressure to said cylinder, a piston in said cylinder, a lathe center slidably operable by said piston extending from said cylinder, a compression spring biasing said piston and said center outwardly. with respect to said cylinder, said means for supplying fluid under pressure including a conduit, a pressure recording gauge in said conduit, a plurality of conduits connecting said pressure gauge with a fluid pressure reservoir, and an automatic valve adapted to be adjusted to a predetermined pressure controlling admission of said fluid through one of said conduits to said cylinder.

3. In a center for lathes in combination, a hydraulic cylinder, means for supplying fluid under pressure to said cylinder, a piston in said cylinder, a lathe center slidably operable by said piston extending from said cylinder, a compression spring biasing said piston and said center outwardly with respect to said cylinder, said means for supsaid conduits are closed.

plying fluid under pressure including a conduit, a pressure recording gauge in said conduit, a plurality of conduits connecting said pressure gauge with a fluid pressure reservoir, a manually operable valve controlling admission of said fluid through one of said conduits and an automatic valve provided with adjusting means to control tending from said cylinder, a compression spring biasing said piston and said center outwardly with respect to said cylinder, said means for supplying fluid under pressure including a conduit and a pressure recording gauge in said conduit, a plurality of conduits connecting said pressure gauge with a fluid pressure reservoir, a manually operable valve controlling admission of said fluid through one of said conduits, an automatic valve controlling admission of said fluid to said cylinder positioned inanother of said conduits, said automatic valve being adjustable, and a pressure pump positioned in still another of said conduits adapted to supply additional fluid under pressure when the valves in said first-mentioned two of LUTHER A. BARTO. 

